3 Monitoring and follow-up
In cooperation with AEE
3.1 General principles and importance of monitoring
The monitoring of the energy consumption in different points of a building is a simple instrument to supervise and to document the performance of all energy consumers and the comfort parameters within an operated building.
By a well-considered monitoring concept (Figure 91) the consumed amount of energy (heat, water, cooling, …) and existing comfort parameters (temperature, humidity, CO2-concentration) are permanently registered and documented in graphics and reports. Based on this information the energy consumptions can be analysed and evaluated. With the help of these monitoring results potential energy savings can be identified, improvement measures and superior activities (like improvements in the building management) can be initiated and supported.
3.2 Analysing building and system performance
In order to analyse the building and system performance and to make statements concerning the energy balance of the building it is necessary to measure different parameters inside and outside the building:
§ Climate data (global radiation, outside temperature, outside humidity)
§ Energy inputs (electricity, natural gas, fuel, pellets, wood chips, ,..)
§ Thermal power in all hydraulic cycles (flow rate, forward and return temperatures)
§ Cold water consumption
§ Consumption of electric power (total amount, ventilation, auxiliary energy, boilers)
§ Temperature and humidity of supply and exhaust air of the ventilation system
§ Comfort parameters in rooms: temperature, humidity, CO2- concentration
Figure 91: Monitoring concept of an office building, sensor positions [AEE08]
For the reporting, documentation and storage of mean values of the energy information a “data logger system” is used, which is supplied with measurement data from the sensors in short time intervals. Figure 92 illustrates the different steps taken in a data logger system.
Figure 92: Data logger system [AEE08]
3.3 Analysing user comfort and behaviour
Based on the measurement data
of the
monitoring system the compliance of calculated and measured comfort
data can be
checked.
For example the figure above shows the compliance of measured room temperatures with defined comfort parameters. Measurement points lying within the orange field meet the common comfort requirements. It can be recognized that on summer days with intensive sun radiation the temperatures of some office rooms climb above the comfort limit (for example, 26°C in Austria). In this case the implementation of additional cooling load reduction measures such as flexible shading devices for summer months should be recommended.
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Figure 93: Distribution of the mean room temperatures (ordinate) in offices as a function of the outside temperature (abscissa) [AEE08]
The same investigation can be made concerning the compliance of measured indoor air humidity with calculated comfort limits. In most cases the ventilation system has to be adjusted during the initial operation period according to the needs of the occupants. If necessary the required adjustments to the ventilation unit can be determined from the monitoring results of supply and exhaust air temperatures and humidity.
Energy monitoring can also lead to the detection of false user behaviour in the buildings. For example, if rooms are permanently overheated in summer although adequate shading devices are installed, users might use them in the wrong way. In this case further information has to be provided for the users.
3.4 References
[AEE08] AEE INTEC / ESTIF, http://www.aee-intec.at/